Novel cationic starch derivatives



United States Patent 2 Claims. (Cl. 162-175) ABSTRACT OF THE DISCLOSURE'This invention relates to the manufacture of paper whereby a novelcationic starch, prepared by reacting starch with ethyleneimine, isadded to a dispersion of pulp and the paper composition thereof.

This application is a division of my copending application Ser. No.354,114, filed Mar. 23, 1964, now Patent No. 3,331,833.

This invention relates to a method for improving the properties andperformance of tertiary amino alkyl starch ethers and, particularly, tothe novel derivatives thus produced.

It is the object of this invention to provide novel derivatives oftertiary amino alkyl starch ethers, said derivatives being characterizedby their improved performance when utilized as wet-end additives in themanufacture of paper wherein their presence yields superior pigmentretention along with an overall increase in the strength of theresulting paper. Various other objects and advantages of this inventionwill be apparent upon a reading of the disclosure which followshereinafter.

In US. Patent 2,813,093, Nov. 12, 1957, Ser. No. 360,818, filed June 10,1953, there is described a method for preparing a novel class ofcationic tertiary amino alkyl starch ether derivatives corresponding tothe formula:

1 XORI IR wherein X is starch, R is a radical selected from the groupconsisting of alkylene and hydroxyalkylene radicals, and each of R and Ris a radical selected from the group consisting of alkyl, aryl andaralkyl radicals. Hereinafter, it is to be understood that whenreference is made to tertiary amino alkyl starch ethers it is the abovedescribed derivatives which are being referred to.

The above described derivatives have been employed in a wide variety ofapplications but have been especially useful as beater and/or headboxadditives in the manufacture of paper wherein their inherent cationiccharge significantly improves the retention of inorganic pigments by thecellulose pulp and substantially increases the ultimate strength of thefinished paper. Of late, however, various attempts have been made in aneffort to still further improve upon the overall performance of thesenovel starch derivatives so as to permit their use at lowerconcentrations While still providing comparable or superior results.These efforts at improvement of the tertiary amino alkyl starch ethershave involved various treatments such as esterification, etherification,cyanoethylation, amidoethylation or hydroxypropylation and have, so far,proven to be ineffective and/or detrimental.

I have now discovered that the novel class of derivatives resulting fromthe reaction between the above described tertiary amino alkyl starchethers with ethyleneimine offer a surprisingly improved degree ofperformance over the tertiary amino alkyl starch ether bases from whichthey are prepared. The novel derivatives of this in- 3,354,034 PatentedNov. 21, 1967 "ice vention are thus those starch derivativescorresponding to the following formula:

A wherein X is starch, R is a radical selected from the group consistingof alkylene and hydroxyalkylene radicals, each of R and R is a radicalselected from the group consisting of alkyl, aryl and aralkyl radicals,and n is an integer having a value which is at least 0.1.

The novel derivatives of this invention may thus be described astertiary amino alkyl starch ethers having one or more substituent sidechains, each of which has at least 0.1 or. more ethyleneimine units,i.e.

each of said side chains being grafted onto the starch molecule via ahydroxyl group of said starch molecule. It

may also be noted that it is possible for a small proportion of theethyleneimine side chains to be grafted onto the starch molecule via thesubstituent tertiary amino alkyl group in which case these novelderivatives would have a ructure selected from the following group:

CHr-CHPNH:

wherein X, R, R R and n are identical in meaning to the correspondingsymbols in the above given formula and wherein R is a radical selectedfrom the group consisting of the -CH CH NH CH and CH CH radicals Forpurposes of brevity, ethyleneimine will be, in this disclosure,hereinafter referred to by the abbreviation EKEI.)

The tertiary amino alkyl starch ethers which, in essence, comprise thestarch bases or intermediates for the novel starch reaction products ofthis invention are more specifically exemplified by the dialkyl aminoalkyl and dialkyl aminohydroxyalkyl ethers of starch as well as by theircorresponding aryl and aralkyl derivatives. Of particular interest foruse as a base in the process of the subject invention is the diethylamino ethyl ether of starch which is produced by the reaction of starchwith diethyl amino ethyl chloride hydrochloride. In general, this classof tertiary amino alkyl starch ethers are prepared by etherifying astarch with an etherifying agent selected from the group consisting ofdialkyl amino alkyl halides, dialkyl amino alkyl epoxides and thecorresponding compounds containing aryl groups in addition to the alkylgroups. In practice, these derivatives are often prepared in the form oftheir acid salts such, for example, as their hydrochloride salts, byconducting the reaction with the acid salt of the chosen etherifyingagent and subsequently neutralizing the resulting derivative with anacid. These tertiary amino alkyl starch ethers may also be subsequentlytreated so as to be converted into their quaternary ammonium salts andboth the quaternary ammonium salts and the acid salts of these tertiaryamino alkyl starch ethers, as well as the free amine form of thesestarch ethers, may be used in preparing the novel derivatives of thisinvention. Moreover, one may also employ pre-gelatinized, i.e. coldwater soluble, forms of these tertiary amino alkyl starch ethers whichmay be prepared, for example, by passing their aqueous slurries overheated metal drums.

The etherifying reaction utilized for the preparation of these tertiaryamino alkyl starch ethers may be conducted on any amylaceous substancesuch as untreated starch as well as starch conversion products andstarch derivatives including dextrinized, hydrolyzed, oxidized,esterified, and etherified starches still retaining amylaceous material.These starches may be derived from any sources including corn, wheat,potato, tapioca, waxy maize, sago, rice, and high amylose corn as wellas the amylose and amylopectin fractions of any of the latter starchsources. Additional information relating to the preparation of thesetertiary amino alkyl starch ethers may be obtained by consulting US.Patent 2,813,093.

Although the concept of reacting EI with polyhydroxy compounds such ascellulose, polyvinyl alcohol and raw starches is admittedly old in theart, it is nonetheless extremely surprising that from among all of themany reagents which have heretofore been used to treat the abovedescribed tertiary aminol alkyl starch ethers in an effort to improvetheir performance as papermaking additives, only E1 was found to becapable of effecting the desired results.

It is also interesting to note that the presence of the tertiary aminoalkyl substituent group in the novel products of this invention plays anessential part both with respect to their actual preparation as well aswith respect to their performance as paper making additives. Thus, withregard to the reaction utilized in their preparation, the teachings ofthe prior art as exemplified respectively by Kerr and Neukom in DieSt'eirke, 4, 10,255; and US. Patents 2,972,606 and 2,656,241, havedisclosed, and I have confirmed, that the treatment with E1 of raw,underivatized starches, as well for that matter as the treatment with E1of other polyhydroxy compounds such as cellulose and polyvinyl alcohol,is ordinarily enhanced by the presenceo-f a suitable catalyst in thereaction system in order to be able to obtain a reaction resulting inany appreciable increase in the nitrogen content of the resultingderivative over that of the raw starch base. In my novel process, on theother hand, I have achieved remarkable increases in the nitrogen contentof my novel derivatives over the nitrogen content of their tertiaryamino alkyl starch ether intermediates without the need for employingany additional catalysts. As for their performance as paper additives, Ihave found that the products resulting from the reaction of El with rawstarch have only limited ability to function as pigment retention agentsand they effect only slight increases in the strength of the resultingpaper sheets. In contrast, my EI derivatives of tertiary amino alkylstarch ethers are exceedingly effective pigment retention agents andproduce a considerable increase in the strength of the resulting sheets.

It may be noted that in addition to El, certain of its low molecularweight alkyl homologs may also be used in the process of this invention.These applicable homologs include, for example, propyleneimine,N-butylethyleneimine; 2-methylethyleneimine; 2,2-dimethylethyleneimine,trimethyleneimine, and N-methylethyleneimine. The use of these homologsis, however, of less interest in the process of this invention ascompared with the use of E1 inasmuch as they are more expensive thanE'I, react with less efficiency and provide derivatives which ordinarilylack an adequate degree of dispersibi'lity in water which would permittheir convenient use as paper making additives. In view of thesedeficiencies, the process of this invention will be, hereinafter,described solely in relation to the use therein of B1.

In brief, the actual process utilized for the preparation of the novelderivatives of this invention comprises the reaction of El with atertiary amino alkyl starch ether which is, preferably, in suspension inan inert organic solvent medium.

The latter suspensions should contain from about 16 to by weight, of theselected tertiary amino alkyl starch ether. As for the solvent, one maychoose any organic solvent which is non-reactive with E1 and does notyield inhibited products under the conditions which will be encounteredin the process of this invention. In effect, the solvent acts as adiluent for the El, thus promoting a uniform distribution of reagent andpreventing any swelling of the starch. In fact, reaction efiiciency maybe additionally enhanced by further diluting the concentration of E1 inthe system by conducting the reaction by means of a so called slowaddition technique whereby rather than introducing the entireconcentration of El into the system at the start of the reaction, it isinstead slowly added, in small increments, over a period of about 15 to30 minutes.

Applicable solvents for use in the reaction include such non-polarsolvents as toluene, chloroform, heptane, and hexane as well as suchpolar solvents as triethylarnine, dimethylformamide, dioxane, anddimethylsulfoxide and, preferably, mixtures of a polar and a non-polarsolvent such, for example, as a mixture of toluene with dioxane or oftoluene with dimethylformamide. Thus, I have found that the use, in theprocess of my invention, of such mixtures of polar with non-polarsolvents results in a surprising increase in the efiiciency of thereaction as indicated by a higher nitrogen content in the resultingderivatives. The reaction efficiency with these solvent blends is, infact, substantially higher than the results which are achieved by thesole use of either a polar or a non-polar solvent.

In another variation of the above described basic pro- 'cedure, one mayutilize a so-called dry technique wherein one sprays or otherwisecontacts a dry mass of the tertiary amino alkyl starch ether with asolution of the E1 dissolved in any of the above listed solvents orsolvent mixtures.

I have also found that an unexpected improvement of the dispersibility,in Water, of the products of my invention may be obtained byimpregnating the tertiary amino alkyl starch ether base in an aqueoussolution of a polyvalent metal salt prior to the reaction of the starchbase with El. Particularly useful for this purpose is stannic chloridealthough other salts, such as aluminum chloride and titanium chloridemay also be used.

In conducting this impregnation procedure, the tertiary amino alkylstarch ether base should be suspended, with agitation, in an aqueoussolution of the selected salt for a period of about 15 to minuteswhereupon the starch ether base should be recovered by filtration anddried prior to its reaction with the El. This procedure is quite helpfulin making non-inhibited, i.e. readily dispersible, non-crosslinked,products in those cases where the tertiary amino alkyl ether is a potatostarch base and especially in procedures where the E1 is to be sprayedonto a dry mass of such a potato starch base.

As noted earlier, one may employ the acid salts, such as thehydrochloride salt, as well as the free amine form of the tertiary aminoalkyl starch ethers in conducting the process of this invention. It has,however, been observed that the use of the acid salts of these starchethers results in higher reaction efficiencies as the acid group ofthese salts appears, in some way, to be accelerating the reaction andpromoting its overall efliciency. It is, therefore, preferred to employthese acid salts of the tertiary amino alkyl starch ethers in preparingthe novel derivatives of my invention.

The concentration of E1 which may be used in the process of my inventionmay vary from as little as about 0.05 up to about of E1 as based uponthe weight of the tertiary amino alkyl starch ether undergoing reaction.Although still higher concentrations may be employed, there are noadvantages to be derived therefrom.

and the cost of the resulting products becomes economically prohibitive.

According to Kerr and Neukom, the reaction of E1 with starch will, inthe absence of a catalyst, yield products having only simplesubstitution and no grafting of ethyleneimine side chains onto thestarch molecule. On the other hand, according to US. Patent 2,972,606,the reaction of cellulose with El does, in the presence of catalysts,result in grafting. Thus, since the tertiary amino alkyl starch etherbases utilized in my novel process contain tertiary amine groups whoseacid salts, as noted above, act to accelerate the reaction and alsoserve as possible sites for substitution, it is therefore, entirelyreasonable to assume that some grafting of ethyleneimine side chainsonto the starch molecule is taking place in the process of my invention.This expectation is particularly valid when higher concentrations of E1,in the order of about or more, on the weight of the starch base areused. Moreover, the rate of grafting will ordinarily be directly relatedto the amount of tertiary amino alkyl substitution which is present inthe starch ether base.

However, regardless of he amount of grafting which occurs, the resultingproducts of my invention exhibit a degree of performance in the papermaking process which is, surprisingly, superior to the results obtainedwith either the EI-starch derivatives made according to the teaching ofKerr and Neukom or the tertiary amino alkyl starch ethers which areutilized as the starting materials in the process of my invention.

It may also be noted that the use of concentrations of E1 above about30%, by weight, of the tertiary amino alkyl starch ether base, resultsin gelatinized, i.e. cold water swelling, reaction products as isfurther attested to by the fact that the polarization cross of theirindividual starch granules has been substantially lost. As might beexpected, the performance of my derivatives as paper making additivesincreases in a direct relation to the concentration of 131 which is usedin their preparation, and also upon the amount of nitrogen which is,according- 1y, introduced therein.

The reaction between the E1 and the tertiary amino alkyl starch ethermay be conducted at temperature ranging from about 25 to 100 C. Althoughstill higher temperatures may be utilized, care must be taken in orderto avoid degradation of the starch ether base. Moreover, the use oftemperature considerably above 100 C. will necessitate employing highpressure equipment. For optimum results, it is preferred to conduct thisnovel process at temperatures in the range of about 40 to 60 C. Withregard to the overall length of the reaction period, I have found thatat about 25 C., about 72 hours is required for the completion of thereaction whereas at 60 C., the reaction is essentially complete afterabout 22 to 24 hours.

Upon the completion of the reaction, the novel derivatives resultingtherefrom may be readily recovered by filtration or decantationwhereafter they need merely be washed with successive portions ofmethanol until the washing are found to be free of alkalinity asindicated by the absence of an alkaline reaction to pH paper. Thederivatives may then be dried by any convenient means.

The novel cationic starch derivatives resulting from the process of myinvention are, as noted earlier, superior in their performane as papermaking additives to the tertiary amino alkyl starch ethers from whichthey are derived. Thus, I have found that their use as beater additivesprovides increased pigment retention along with an overall increase inthe strength of the resulting paper sheet as compared to the resultsobtained by the use of an equivalent concentration of the tertiary aminoalkyl starch ether. This superior performance thereby permits the use oflower concentrations of my derivatives in the paper making process. Inaddition to their use as wetend additives, the products of my inventionmay also be employed in various other applications such as coatingbinders, fiocculants, textile sizes and finishes, and as adhesives.

Although this disclosure has been limited to the products resulting fromthe reaction of El with the above described tertiary amino alkyl starchethers, it should be noted at this point that comparable products mayalso'be prepared by the reaction of E1 with: (a) the sulfonium starchethers disclosed in US. Patent 2,989.,- 520, and (b) the phosphoniumstarch ethers disclosed in U.S. Patent 3,077,469.

The following examples will further illustrate the process of thisinvention. In these examples, all parts given are by weight, unlessotherwise noted.

Example I.This example illustrates the preparation of several of thenovel derivatives of my invention and also demonstrates their improvedperformance as pigment retention aids in comparison with the tertiaryamino alkyl starch ether base from which they were derived.

In preparing these derivatives, parts of the hydrochloride salt of thediethyl amino ethyl ether of corn starch, as prepared by the reaction ofcorn starch with 3.0% by weight of beta-diethyl amino ethyl chloridehydrochloride by means of the procedure described in Example I of US.Patent 2,813,093, were in each case suspended in parts of heptane and,with agitation, reacted with varying concentrations of E1 at atemperature of 60 C. over a period of 24 hours. Each of the resultingreaction products was then recovered by filtration, washed with methanoluntil the washing showed no alkaline reaction to pH paper, and finallydried. In all cases, the resulting derivatives yielded aqueousdispersions which did not settle out or form cloudy layers on prolongedstanding.

These derivatives were then utilized as paper making additives by beingintroduced into the beater or head box during the normal course of thepaper making process. In each case, the pulp batch to which thederivative was added also contained 10% of titanium dioxide as based onthe dry weight of the pulp. The degree of retention of the latterpigment in the resulting paper sheets was then determined by ashing thepaper and weighing the resulting ash.

The following table provides data relating to the concentration of Elwhich was utilized for the preparation of each of the derivatives; thenitrogen content ona dry basis of the resulting derivative which is tobe compared with the nitrogen content of the tertiary amino alkyl etherbase which in all cases was 0.25% by weight on a dry basis; theconcentration of the derivative which was added to the pulp as based onthe dry weight of the pulp; and, the percent retention of the pigment inthe various paper sheets prepared with the respective derivatives. Thefirst and fourth lines in this table provide a comparison of the resultsobtained by the use, in the same manner, of the tertiary aminoalkylstarch ether base.

Percent EI Percent Ni- Percent De- Percent Re- Derivative on Base trogenin rivative tention of No. Derivative Added to Titanium (on dry basis)Pulp Dioxide This procedure was con'lucted as a dry reaction by sprayingthe starch base with a solution of 20 parts of El dissolved in 40 partsof dimethylforrnaruide.

?This procedure was identical to the above described dry reaction withthe exception that the solvent for the E1 was triethylarnine rather thandimethylformamide.

3 In this procedure the El was slowly added to the starch suspension insmall increments over a 30 minute period.

The above data clearly indicate the superior pigment retention which isachieved by the use of the novel derivatives of my invention as comparedwith the results obtained by the use, as paper making additives, of thetertiary amino alkyl starch ethers from which these derivatives wereprepared. Also demonstrated is the fact that as the concentration of theEl used in preparing these derivatives is increased, there is acorresponding rise in their performance as pigment retention aids. Thus,for example, with a derivative of my invention prepared by the use of60% of El, as based on the weight of the starch base, i.e. DerivativeNo. 6, it is possible to obtain almost a 10% improvement in pigmentretention while using 75 by weight, less of the derivative than of itstertiary amino alkyl ether base.

Example II.--This example illustrates the preparation of my novelderivatives utilizing a variety of dilterent tertiary amino alkyl etherbases.

The following table describes the various tertiary amino alkyl starchethers which were employed in preparing these derivatives.

Description Base No.:

(1) The free amine form of the diethyl amino ethyl ether of corn starchis prepared by means of the procedure described in Example II of U.S.Patent 2,813,093.

(2) The quaternary ammonium salt of the diethyl amino ethyl ether ofcorn starch prepared by reacting the hydrochloride salt of the diethylamino ethyl ether of corn starch with 50% by weight of methyl iodideaccording to the procedure described in Example VI of U.S. Patent2,813,093.

(3) The hydrochloride salt of the diethyl amino ethyl ether of tapiocastarch as prepared by means of the reaction described in Example III ofU.S. Patent 2,813,093.

(4) The hydrochloride salt of the diethyl amino ethyl ether of a cornstarch which had previously been oxidized with sodium hypochlorite to adegree known in the trade as 87 fluidity, as prepared by means of theprocedure described in Example 111 of U.S. Patent 2,813,093.

(5) The hydrochloride salt of the dimethyl amino isopropyl ether of cornstarch which had previously been acid converted to a degree known in thetrade as 60 fluidity, as prepared by means of the procedure described inExample IV of U.S. Patent 2,813,093.

(6) The hydrochloride salt of the dibutyl amino 2-hydroxypropyl ether ofcorn starch, as prepared by means of the procedure described in ExampleV of U.S. Patent 2,813,093.

(7) The hydrobromide salt of the 2-bromo-5-diethyl amino pentane etherof corn starch, as prepared by means of the procedure described inExample VII of U.S. Patent 2,813,093.

(8) The hydrochloride salt of the diethyl amino ethyl ether of sagostarch, as prepared by means of the procedure described in Example VIIIof U.S. Patent 2,813,093.

(9) The hydrochloride salt of the dioctyl amino ethyl ether of cornstarch, as prepared by means of the reaction described in Example XI ofU.S. Patent 2,813,093.

(10) The 3-(N-methy-l-N-phenyl)-amino 2 hydroxypropyl ether of cornstarch.

In reacting the above described tertiary amino alkyl starch ether baseswith EI, the following procedure was employed:

A sample of 100 parts of each base was sprayed with 20 parts of EI whichhad been diluted with 20 parts of triethylamine and thereupon reacted at60 C. for a period of 24 hours. Each of the resulting reaction productswas washed repeatedly with methanol until the washings were found to bedevoid of any alkalinity whereupon it was dried. Other solvents, such asheptane, toluene and dimethylformamide were also used in variousrepetitions of these reactions.

In all cases, the derivatives resulting from the use of the abovedescribed intermediates in the process of my invention were found todisplay improved results as paper making additives in comparison withthe results obtained when their underivatized intermediates wereutilized.

Example IIl.This example illustrates the use of a number of the loweralkyl homologs of E1 in preparing the novel derivatives of my invention.

Part A.In this procedure, parts of the hydro chloride salt of thediethyl amino ethyl ether of corn starch were suspended in 600 parts ofheptane to which suspension there was then added a solution of 57 partsof N-methylethyleueimine in 100 parts of heptane. The reaction wasconducted, under agitation, at a temperature of 60 C. over a period of16 hours. The product was recovered by filtration, washed with methanoluntil free of alkalinity and then dried. The resulting derivative had anincrease in its nitrogen content of only 1.94%, by Weight on a drybasis, versus a calculated increase of 8.9% over the nitrogen content ofthe starch ether base in spite of the high concentration ofN-methylethyleneimine which had been utilized in its preparation.Moreover, this derivative displayed a rather limited degree of waterdispersibility.

Part B.In this procedure, the reaction was conducted in a manneridentical to that described for Part A, hereinabove, with the exceptionthat 72 parts of 2,2-dimethylethyleneimine were utilized in place of the57 parts of N- methylethyleneimine. The resulting derivative had anincrease in its nitrogen content of only 1.26%, by weight on a drybasis, over the nitrogen content of the starch ether base in spite ofthe high concentration of 2,2-dimethylethyleneimine which had beenutilized in its preparation. Moreover, this derivative displayed only arather limited degree of water dispersibility.

The properties of the above described derivatives serve to indicate thatthe use of the lower alkyl homologs of El does not give resultscomparable to those obtained by the use of E1 in the process of thisinvention.

Example I V.-This example compares the performance of the productsobtained upon the reaction of El with ordinary starch with theperformance obtained utilizing the novel products of my inventioncomprising the reaction products of El with the above described tertiaryamino alkyl starch ethers. In each of the following experiments,bleached sulfite pulp having a freeness of 400 was utilized in aconcentration of about 0.5% by weight, while the concentration of thetitanium dioxide was 10% as based upon the bone dry weight of the pulp.

Part A.In this procedure, the technique of Kerr and Neukom was followedand 100 parts of raw corn starch were suspended in parts of heptane and,with agitation, reacted with 50 parts of El at a temperature of 60 C.over a period of 24 hours. The resulting reaction product was recoveredby filtration, Washed with methanol until the washings showed noalkaline reaction to pH paper, and then dried. This derivative wasthereupon utilized as a pigment retention aid in the manner described inExample I, hereinabove. It was added to the headbox in a concentrationof 0.25%, as based on the dry weight of the pulp which also contained10%, by weight, of titanium dioxide. Analysis of the resulting papersheets indicated a degree of pigment retention of 66%. It may also benoted that this derivative displayed a poor degree of waterdispersibility.

Part B.In this procedure, 100 parts of raw corn starch were suspended in200 parts of dimethylformamide in which there were also dispersed, as acatalyst for the reaction, 0.8 part of stannic chloride pentahydrate.With agitation, the starch was then reacted with 60 parts of El at atemperature of 60 C. for a period of 24 hours. The resulting reactionproduct was recovered by filtration, washed with methanol until thewashings showed no alkaline reaction to pH paper, and then dried. Thisderivative was thereupon utilized as a pigment retention aid in themanner described in Example I, hereinabove. It was added to the beaterin a concentration of 1.0%, as based on the dry weight of the pulp whichalso contained by weight, of titanium dioxide. Analysis of the resultingpaper sheets indicated a degree of pigment retention of 60.8%. It mayalso be noted that this derivative displayed a poor degree of waterdispersibility.

The performance, as pigment retention aids, of the above describedreaction products of E1 with raw corn starch is thus seen to be quiteinferior with respect to the results obtained with the novel derivativesof my invention as illustrated by the pigment retention data presentedin Example I, hereinabove. The present results thus point out thecriticality of using only the specified tertiary amino alkyl starchethers as the intermediates for the preparation of the novel derivativesof my invention.

Example V.-This example illustrates the increased reaction efliciency,as evidenced by a higher nitrogen content in the resulting derivatives,which results from the presence of higher concentrations of tertiaryamino alkyl groups in the starch bases utilized in the process of thisinvention.

A number of 100 part portions of difi'erent diethyl amino ethyl ethersof potato starch having varying nitrogen contents, as indicated below,were reacted, respectively, for 24 hours at 60 C., with 100 parts of EIin 100 parts of a solvent mixture comprising a 2:1:1:1chloroform:triethylamine:dioxanerheptane blend. The resulting productswere washed with successive portions of methanol and then air dried.

The following table provides data relating to the nitrogen content ofthe starting starch ether bases versus the nitrogen content of theproducts derived therefrom.

Percent Diethyl Percent Total Percent Nitrogen Amino Ethyl Nitrogen inIntroduced via Re- Nitrogen Product action with EI 1 Control comprisingraw potato starch.

Example VI.-This example illustrates the improved reaction efiiciency,in the process of my invention, which results from the use, as areaction medium, of a blend of a polar with a non-polar solvent.

Using the reaction procedure described in Example V, hereinabove, 20parts of E1 was reacted, respectively, with a number of 100 partportions of the identical diethyl amino ethyl ether of potato starch.Each of the various samples was, however, reacted in 20 parts of adifferent solvent or solvent blend. The following table identifies thesolvents or solvent blends which were used and also indicates thepercent total nitrogen which was present in the resulting reactionproducts.

Percent total nitro- Solvent used: gen in product 100% toluene 3.88

An 80:20 t-oluene:dimethylformamide blend 4.38

A 50:50 toluenezdimethylformamide blend 4.59 100% dimethylformamide e3.93

Example VII.This example illustrates the improved dispersibility, inwater, resulting from the impregnation of the starch ether base in asolution of a polyvalent metal salt prior to the reaction of the basewith EI.

A number of 100 part portions of different diethyl amino ethyl ethers ofpotato starch having varying nitro- 10' gen contents, as indicatedbelow, were suspended, respectively, in solutions comprising 0.5 part ofstannic chloride dissolved in parts of water which was at a temperatureof 25 C. Each suspension was agitated for 15 minutes whereupon thestarch base was recovered by filtration and air dried.

The recovered starch bases were then reacted with EI according to theprocedure described in Example V, hereinabove. As a control for theexperiment, portions of the identical starch ether bases which, in thiscase, had not been suspended in stannic chloride solutions, were thensimilarly reacted with EI.

The dispersibility of each of the thus prepared products was thenevaluated by means of a settling test which involved cooking a 0.1%, byweight, aqueous dispersion of each product, for a period of 15 minutes,over a boiling water bath. The cooked dispersions were then placed intoa series of 100 milliliter graduated cylinders and allowed to stand for16 hours at room temperature. The appearance of a dense, cloudy layer atthe bottom of the cylinder would thus indicate poor dispersibilitywhereas the absence of such a dense, cloudy layer would indicate gooddispersibility. The following table presents the results of these tests.

The above data indicate that although the impregnation in stannicchloride resulted in a slightly poorer reaction efficiency, as indicatedby the lower nitrogen content of the resulting derivatives, thedispersibility of the products derived from the impregnated bases wasfar superior to the dispersibility observed in the controls.

Summarizing, this invention is seen to provide a process for thepreparation of novel cationic starch derivatives. Variations may be madein proportions, procedures and materials without departing from thescope of this invention which is limited only by the following claims.

What is claimed is:

1. A cellulosic paper having intimately dispersed therein a novelcationic starch derivative having the structural formula:

wherein X is starch, R is a radical selected from the group consistingof alkylene and hydroxyalkylene radicals, each of R and R is a radicalselected from the group consisting of alkyl, aryl and aralkyl radicals,and n is an integer having a value of at least 0.1; said derivativecontaining on a dry basis from about 0.08 to 10.0% by Weight ofnitrogen.

2. In the manufacture of paper wherein an aqueous dispersion of pulp isformed into a sheet, the step which comprises adding to the aqueousdispersion of the pulp, prior to the ultimate removal of the watertherefrom, a novel cationic starch derivative having the structuralformula:

3,3545034 1 1' 12 consisting of alkylene and hydroxyalkylene radicals,each No references cited. of R and R is a radical selected from thegroup consisting of alkyl, aryl and :aralkyl radicals, and nis aninteger DONA D E. C AJ A, Primary Examiner.

having a value of at'least 0.1; said derivative containing LEON I.BERCOVITZ, Examiner.

on a dry basisfrorn about 0.08 to 10% by weight of 5 nitrogen, R. W.MULCAHY, Assistant Exammer.

1. A CELLULOSIC PAPER HAVING INTIMATELY DISPERSED THEREIN A NOVELCATIONIC STARCH DERIVATIVE HAVING THE STRUCTURAL FORMULA: